'A British military attack on Syria will have to be a "judgement call" as there is no "single smoking piece of intelligence" that the regime used chemical weapons, David Cameron said at the beginning of the emergency Commons debate on Syria'So Cameron has made it clear that he is Prime Minister and he will make the 'judgement call'. It is a similar position to Tony Blair 'believing' that the invasion of Iraq was 'right' and when he took the decision it was voted for by Parliament. It is Washington that decides and the Parliamentary debates are largely irrelevant.
None of the party political leaders is against the use of military strikes on principle. Cameron is claiming essentially that he believes Assad used chemical weapons and that inaction is not an option. Miliband is attacking the exact manner in which Cameron has proceeded to make the case for intervention.
The case for military intervention itself is not subject for debate. Only the demand from Milband that it follows due procedures that Cameron is not denying will be attempted but that UN security council mandates are not necessary because of the role of 'the responsibility to protect' and prevent a humanitarian disaster.
The second vote is when it really matters and what actually counts. If Washington decided the evidence is satisfactory for a military strike to proceed, then the question is whether Parliament will defy Cameron and whether the Labour leadership will reject any 'compelling evidence' the US government provides.
Cameron is just 'on message' from Washington about the issue of there being 'no smoking gun'. i.e no definitive piece of evidence proving Assad intentionally and explicitly carried out a rocket attack using chemical weapons. The Labour amendments were still about framing the possible case for military action
US officials have already indicated that if Britain does not give Washington support, it would be prepared to act anyway. Harf stated robotically a few hours ago '“We make our own decisions and our own timeline". So that is that then and what politicians here decide would not affect the USA's response
Little Parliament does or does not do will affect Washington's line. White House spokesman Josh Earnest said "When the president reaches a determination about the appropriate response ... and a legal justification is required to substantiate or to back up that decision, we'll produce one on our own."
The second motion in Parliament will take what Washington does into consideration and if it determined to launch a military strike there is little chance that Miliband would vote against it or defy Washington as it will find a 'legal basis' and put out the sort of 'public diplomacy' Miliband could accept.